This invention relates to a method of constructing a dipole magnet with superconducting wire.
Dipole electromagnets are used in accelerators of charged particles to meet many needs. A magnetic field that increases in synchronism with the increasing acceleration of a charged particle is used in a synchrotron to maintain a constant orbit for particles that are being accelerated. Particles are injected into an accelerator along a path that is controlled by a dipole injection magnet. Accelerated particles are directed to desired locations by dipole bending magnets. The design of such magnets has heretofore been the subject of many computer studies to maintain a high degree of precision of the field in two ways. First, it is often desirable to have high uniformity of magnetic field across a cross section of the dipole magnet. This insures that particles anywhere within the field experience the same amount of bending for the same particle momentum. Second, it is often desirable that the magnetic field of the magnet fall uniformly to zero in an axial direction while maintaining equality of the fields across the cross section. This causes the magnet to bend but not to focus or defocus the beam.
Two basic approaches have been taken toward meeting the requirements described above in the construction of dipole electromagnets for particle accelerators. Almost all of the magnets thus far built for this purpose have used conventional electrical conductors and most of these have included iron cores to locate the magnetic fields in desired gaps. The first of these approaches has been to shape the pole faces of the iron cores to provide various gradients of magnetic fields in the gaps. For example, weak-focusing synchrotrons have gaps in accelerating dipole magnets that are substantially parallel. Magnets for strong-focusing synchrotrons typically have tapering gaps with the directions of the tapers altering from section to section. Either type of dipole magnet requires application of some form of focusing correction to the beam to make up for the effects of leaving the field of the dipole magnet. This may be accomplished by shaping the exit pole faces of the magnet or it may be accomplished by the installation of focusing magnets to make up for the defocusing effects that result from leaving an unshaped magnet. Both of these approaches involve considerable complexity in design and add control complications in the operation of the accelerators in which the magnets are used. In the case of the shaped ends of accelerating magnets in a weak-focusing synchrotron, the shape is of necessity a compromise between the terminations of the magnets that are desirable at low magnetic fields and those needed at high magnetic fields. In the case of strong-focusing synchrotrons, the focusing fields must be programmed to vary with the varying strength of the accelerator field during the ramp of each pulse. This adds extra magnets to be placed under the control of the accelerator control system and thus adds an extra complication.
It is an object of the present invention to provide a better dipole electromagnet for a particle accelerator.
It is a further object of the present invention to provide a superconducting dipole magnet with an air core.
It is a further object of the present invention to provide a superconducting magnet having spatially uniform decrease to zero of the magnetic field at the ends of the magnet and a uniform magnetic field along each cross section.
It is a further object of the present invention to provide a method of winding a better superconducting dipole magnet.
Other objects will become apparent in the course of a detailed description of the invention.